WSP03103

• File Number: 8276.100
• Description: Grand Valley Unit-Colorado River Basin Salinity Control Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 3/1/1980
• Title: Salinity Control Program - Grand Valley Unit
• Water Supply Pro - Doc Type: Report/Study

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Summary

The Colorado River drains 242,000 square miles in thE, United States and
2,000 square miles in Mexico. The Colorado River Basin includes parts of
seven states: Wyoming, Colorado, Utah, Nevada, New Mexico, Arizona, and
California. From this area, it carries a salt load of 10 million tons an-
nually. Each square mile above the Grand Canyon contributes an average of
70 tons of salt to the river each year. This salt loading is due to natural
and manmade causes. The water is used and reused several times along its
1,400-mile length, resulting in decreased volume of available water but in-
creased salinity. The demands on the river exceed its dependable supply.
In overall terms, the high salinity in the lower reaches of the river adverse-
ly affect about 10,000,000 people and about 1,000,000 acres of fertile irriga-
ted farmland.

Increased salinity in the Colorado River is not a new or unique situation
in the history of western water resources. It has been the obj ect of several
past studies and investigations. Various aspects of the problem and control
measures have been pursued by the Water & Power Resources Service (formerly
Bureau of Reclamation), Geological Survey, Environmental Protection Agency,
(and its preceding agencies), the Water Resources Council, the Colorado River
Board of California, and several universities. Studies spanning many years
have traced historic salinity levels and flows, sources, and the nature and
magnitude of damages and potential control measures. The largest portion of
the mineral burden and water supply originates in the Upper Colorado Basin.

In 1972, the Colorado River Water Quality Improvement Program was begun
by the Bureau of Reclamation in cooperation with other Federal agencies and
the seven states of the river basin. The Colorado River Basin Salinity Con-
trol Act of 1974 (Public Law 93-320) established a basinwide program of works
to enhance and protect the quality of water available in .~he Colorado River
for use in the United States and the Republic of Mexico.

Title I of the Act, directed toward controlling the salinity of river
water below Imperial Dam (located in Arizona near the Mexican border) for
use in the United States and Mexico, authorized construction of a desalting
complex and other measures to ensure acceptable salinity levels. Title II,
directed toward salinity control in the United States above Imperial Dam,
authorized construction of the Grand Valley Unit and three other units as the
initial stage of the Colorado River Basin Salinity Control Project. It also
directed that planning reports be prepared for 12 more units. A thirteenth
unit has been added for study since the Act was passed.

All of the provisions of the Grand Valley Unit apply to existing irriga-
tion systems and the lands associated with them. These systems include the
Government Highline, Orchard Mesa, Grand Valley, and Redl,mds Canals, as well
as several smaller canals. Listed below are all of the units in the Upper